SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c3590f1aa64a3274557d54f1614062d4f720f246136551e4e77d7d90dcc4517' 
  AND token = 'cjZxTMuh0vk+5SUKNnR8NYKsI3jVIj0kuEwkRnsQ18M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}